Conduit for electric wires.



R. .8. CASE.

CONDUIT FOR ELECTRIC WIRES.

APPLICATION FILED AUGJ. I911.

1,166,432. I Patented Jan. 4, 1916.

RAYMOND S. CASE, OF UNIONVILLE, CONNECTICUT.

CONDUIT FOR ELECTRIC WIRES.

Specification of Letters Patent.

Application filed August 4, 1911. Serial No. 642,264. g

To all whom it may concern:

vBe it known that I, RAYMOND S. CASE, a citizen of the United States, and a resident of Unionville, in the county of Hartford and State of Connecticut, have invented-a new and Improved Conduit for Electric Wines, of which the following is a specification.

My invention relates to the class of devices above named, and the objects of the invention, among others, are to provide a device of this class that while possessing all of the qualities of strength required in such devices may be constructed at a minimum cost, one in which the opening through the tube shall be extremely smooth, and one which shall compel the use of the structure as originally made.

A form of device in the construction and use of which these objects, as well as others, may b attained is illustrated in the accompanying drawings, in which- Figure 1 is a detail side view of a conduit embodying my invention with parts of the structure broken away to show construction. Fig. 2 is a. view on enlarged scale in central lengthwise section through a portion of a tube. Fig. 3 is a detail view in cross section through the same.

A common form of construction of con duits for electric wires includes a core or inner tube of paper-board spirally wound, this being covered with a. layer of rubber tape, and outside of these a cover of fabric. The paper-board composing the core is of necessity of considerable thickness with a result that as the paper is wound, the inner surface being disposed on a smaller circle than the outer surface, is liable to become wrinkled, or the outer surface must stretch,

this requiring the use of apaper quite ex-- pensive to manufacture, and having qualities to resist this wrinkling and stretching without cracking or breaking. I have demonstrated that this lining tube may be composed of a cheaper grade of paper, and such a structure will have the added result that the inner surface of the tube will be comparative-ly smooth and free from wrinkles.

In constructing a tube in accordance with my invention the inner tube 6 is spirally wound as shown in Figs. 1 and 2 of the drawings, and is composed of a plural number of plies 7 of paper, three plies being shown herein. These plies are of a thickness to provide the required thickness for the inner tube when they are superimposed. In winding this tube the difference between the inner surface and the outer surface of each ply is so slight a's,to put no unnecessary strain upon the strips or plies, and it also avoids the wrinkling on'the inner surface of the tube, and the difference between the inner diameter of the tube and its outer diameter will be taken care of in the different plies, the outer ply requiring to be longer than the inner ply, as illustrated in Fig. l of the drawings, in which is shown a structure of three plies of paper of equal length, and in which it will be seen that the outer plies become continually shorter than the inner ply as the winding progresses. These plies may be secured together in any desired manner, in the form of construction shown an adhesive being placed between the plies to bind them together after the winding operation is com leted. In constructing my improved conduit the usual layer 8 of rubber may be made use of, and the outer covering 9 of fabric employed.

In the installation of electric wires it sometimes happens that the opening in, the conduit is slightly smaller than a Wire to be inserted therein, and workmen frequently strip the core from the conduit in order to make it large enough to receive the wire, with the obvious result of destroying the efliciency of the conduit. In order to obviate such an operation or objectional' use the core included in the spirally wound inner tube,

in either event it effectually preventing the stripping of this inner tube from the conduit.

WVhileI have shown and described herein a preferred construction for carrying out my invention this may be-departed from to a greater or lesser extent without avoiding the invention, and I do not therefore limit the invention to the exact construction herein shown and described.

I claim- A flexible conduit for electric wires comprising a tube formed from a stripof material and an inner layer consisting of, at

Patented Jan. 4., 1916.

Q1 :aw ase least three independent plies of spirally by the strips may be simultaneously wound wound strips of thin paper of uniform and yield longitudinally with respect to thicknesses in' each strip, all being of even each other.

width throughout and having their joints RAYMOND S. QASE. 5 arranged in the same plane, said'strips be- Witnesses:

ing connected by an adhesive, plastic during ARTHUR 1B. JENKINS,

the winding and thereinafter setting Where- E. L. STO GHTON. 

